Surely the most likely scenario by far is that the poor beggar just made a mistake, screwed up, misjudged, cocked up as humans so often do. Who suggests psychological events, confusion with a different machine (the daftest excuse of all, imo) or an automotive equivalent of g-loc when there's a car crash? Never! Driver error, that's it. Is this really likely to be much different?
Indeed, which to be fair was also the conclusion of almost all of those more familiar with air display game. The problem now with Internet forums is that anybody can come up with a 'whacky' hypothesis. As for the 'he was too good to make a mistake', I recall the same being said after poor old Mark H crashed his Buchon in Spain.
Accidents when air displaying will never be eradicated, and the vast majority will be down to an error by the pilot.